The rich vasculature of the nasal mucosa provides a desirable avenue for the introduction of various agents. In particular, the highly vascularized lateral wall of the bulbous portion of the nasal cavity provides a particularly efficient route for absorption or adsorption of such agents.
It is known that absorption or adsorption of a material increases with residence time between the material and epithelial tissue in the nose, or other body cavity. On the other hand, the activity of cilia acts to clear the mucous tissue of dust or other particles trapped in mucous tissue.
Methods for delivery of agents to the nasal membranes include delivery in the form of drops, sprays, powders, or gels. It is also known that increasing the viscosity of a solution of therapeutic agent may have the effect of retaining the agent in the face of cilial action, thereby prolonging the therapeutic effect of the agent, and, thus, gels have come to be used for delivering such agents. Examples of gel-borne agents for nasal delivery are provided in U.S. Pat. Nos. 6,080,783 and 6,365,624, to Davidson et al., which are incorporated herein by reference.
One problem that presents itself, however, is that of optimizing the residence time in a region of particular efficacy, and, at the same time, providing a convenient application modality for the user that is neither messy nor difficult to use.